Authors/Ockham/Summa Logicae/Book III-1/Chapter 30

Latin	English
Cap. 30. Quo modo contingit syllogizare ex propositionibus modalibus aliis quae non ita usitate vocantur modales sicut praedictae	Chapter 30. How it is possible to syllogize from other modal propositions which are not usually called 'modal' in the sense above.
Ostenso quomodo contingit syllogizare per syllogismum uniformem ex propositionibus modalibus quae usitate vocantor modales, restat videre quomodo ex aliis modalibus contingit arguere.	Having shown how it is possible to syllogize by means of a uniform syllogism from modal propositions which I usually call modal, it remains to see how it is possible to argue from other modals.
Est autem primo sciendum quod tales propositions ita possunt habere duos sensus sicut aliae de quibus dictum est. Similiter possunt esse aliquae aequivalentes talibus sensibus compositionis et divisionis. Et ideo pro sensibus compositionis talium propositionum et aequivalentibus eis est ista regula generalis, quod quando aliquod nomen tale modale potest verificari de praemissis absque hoc quod verificetur de conclusione, immo potest vere removeri a conclusione, uniformis ex talibus in sensu compositionis non valet nec ex aequivalentibus eis; quando autem de praemissis non potest verificari talis modus nisi etiam verificetur de conclusione, uniformis ex talibus semper tenet. Et ideo sic arguendo ‘omnem hominem esse animal est verum; Sortem esse hominem est verum; igitur Sortem esse animal est verum’; ‘omnem hominem esse ƿ animal est opinabile vel credibile; Sortem esse hominem est credibile; igitur Sortem esse animal est credibile’, - accipiendo ‘credibile’ pro illo cui intellectus potest assentire, sive evidenter sive non evidenter -, convenienter arguitur. Et hoc quia talis discursus tenet per tales regulas veras ‘praemissae sunt verae, igitur conclusio est vera’; ‘praemissae sunt credibiles, igitur conclusio est credibilis’, praedicto modo accipiendo ‘credibile’.	But it must first be known that such propositions can have two senses just as others of which it was said . Similarly, there can be some equivalents to such senses of composition and division. And therefore for the senses of composition of such propositions and their equivalents there is this general rule, that when some such modal name can be verified of the premises without being verified of the conclusion, or indeed can be truly removed from the conclusion, the uniform from such in the sense of composition is not valid nor from their equivalents; but when such a mode cannot be verified of the premises unless it is also verified of the conclusion, the uniform syllogism from such always holds. And therefore thus arguing ‘that every man is an animal is true; that Socrates is a man is true; therefore that Socrates is an animal is true’; ‘that every man is an animal is conceivable or credible; that Socrates is a man is credible; Therefore, it is credible that Socrates is an animal’, - taking ‘credible’ for that to which the intellect can assent, whether evidently or not evidently -, is suitably argued. And this is because such a discourse holds by such true rules ‘the premises are true, therefore the conclusion is true’; ‘the premises are credible, therefore the conclusion is credible’, taking ‘credible’ in the aforementioned way.
Sed tales syllogismi non valent ‘omnem hominem esse album est scitum ab aliquo; Sortem esse hominem est scitum ab aliquo; igitur Sortem esse album est scitum ab aliquo’; ‘omnem figuram planam tribus lineis contentam habere tres etc. est indemonstrabile; omnem triangulum esse figuram planam etc. est indemonstrabile; igitur omnem triangulum habere tres etc. est indemonstrabile’; ‘omnem intellectum esse animam intellectivam est dubitabile’ vel ‘omnem intellectum esse formam substantialem est dubitabile; aliquam qualitatem, quae non est forma substantialis, esse intellectum est dubitabile; igitur aliquam qualitatem, quae non est forma substantialis, esse formam substantialem est dubitabile’. Et hoc quia tales regulae falsae sunt ‘praemissae sunt scitae, igitur conclusio est scita’; potest enim una praemissa sciri ab uno et alia ab alio et tamen ab utroque ignorari conclusio; ‘praemissae sunt indemonstrabiles, igitur conclusio est indemonstrabilis’; ‘praemissae sunt dubitabiles, igitur conclusio est dubitabilis’.	But such syllogisms are not valid: ‘every man is known to be white by someone; that Socrates is a man is known by someone; therefore, Socrates is known to be white by someone’; ‘every plane figure containing three lines has three etc. is indemonstrable; every triangle is a plane figure etc. is indemonstrable; therefore, every triangle has three etc. is indemonstrable’; ‘that every intellect is an intellective soul is doubtful’ or ‘that every intellect is a substantial form is doubtful; that some quality which is not a substantial form is an intellect is doubtful; therefore, that some quality which is not a substantial form is a substantial form is doubtful’. And this is because such rules are false: ‘the premises are known, therefore the conclusion is known’; for one premise can be known by one and another by another and yet the conclusion is unknown by both; ‘the premises are indemonstrable, therefore the conclusion is indemonstrable’; ‘the premises are doubtful, therefore the conclusion is doubtful’.
Unde ad sciendum quando talis syllogismus est bonus et quando non, valent regulae, tam falsae quam verae, infra scriptae.	Hence, to know when such a syllogism is good and when it is not, the rules, both false and true, written below are valid.
Unde istae regulae sunt falsae: ‘praemissae sunt falsae, igitur conclusio est falsa’; ‘praemissae sunt scitae, igitur conclusio est scita’; ‘praemissae sunt creditae, igitur conclusio est credita’; ‘praemissae sunt indemonstrabiles, igitur conclusio est indemonstrabilis’; ‘praemissae sunt dubitabiles, ergo conclusio est dubitabilis’; ‘praemissae sunt primo verae, igitur conclusio est primo vera’; ‘praemissae sunt per accidens, igitur conclusio est per accidens’; ‘praemissae sunt intellectae, igitur conclusio ƿ est intellecta’; ‘praemissae sunt probatae, igitur conclusio est probata’; ‘praemissae sunt auditae, igitur conclusio est audita’. Et tales consimiles falsae sunt, et ideo uniformis ex talibus propositionibus modal bus non tenet.	Hence these rules are false: ‘the premises are false, therefore the conclusion is false’; ‘the premises are known, therefore the conclusion is known’; ‘the premises are believed, therefore the conclusion is believed’; ‘the premises are indemonstrable, therefore the conclusion is indemonstrable’; ‘the premises are doubtful, therefore the conclusion is doubtful’; ‘the premises are initially true, therefore the conclusion is initially true’; ‘the premises are accidental, therefore the conclusion is accidental’; ‘the premises are understood, therefore the conclusion is understood’; ​​‘the premises are proven, therefore the conclusion is proven’; ‘the premises are heard, therefore the conclusion is heard’. And such similar ones are false, and therefore the uniform does not hold from such modal propositions.
Sed istae regulae sunt verae: ‘praemissae sunt evidenter cognoscibiles, igitur conclusio est evidenter cognoscibilis’; ‘praemissae sunt credibiles, igitur conclusio est credibilis’; ‘praemissae sunt demonstrabiles, igitur conclusio est demonstrabilis’; ‘praemissae sunt verae, igitur conclusio est vera’; ‘praemissae sunt intelligibiles, igitur conclusio est intelligibilis’. Et multae tales. Et uniformes ex talibus modalibus, sumptis in sensu compositionis vel aequivalentibus eis sunt boni, tenentes per talem regulam ‘praemissae sunt tales, igitur conclusio est talis.	But these rules are true: ‘the premises are clearly knowable, therefore the conclusion is clearly knowable’; ‘the premises are credible, therefore the conclusion is credible’; ‘the premises are demonstrable, therefore the conclusion is demonstrable’; ‘the premises are true, therefore the conclusion is true’; ‘the premises are intelligible, therefore the conclusion is intelligible’. And many such. And uniforms from such modals, taken in the sense of composition or equivalent to them, are good, holding by such a rule ‘the premises are such, therefore the conclusion is such.
Si autem praemissae tales sumantur ambae in sensu divisionis in prima figura, semper est syllogismus regulatus per dici de omni vel de nullo quando ex suis de inesse est bonus syllogismus, nisi ratione modi includatur aequivalenter propositio negativa. Quod dico propter istum modum ‘falsum’, et si aliquis alius sit sibi similis. Quia non sequitur ‘omnis lapis falso est animal; omnis asinus falso est lapis; igitur omnis asinus falso est animal’. Similiter iste syllogismus non valet ‘omnem lapidem esse animal est falsum; omnem hominem esse lapidem est falsum; igitur omnem hominem esse animal est falsum’, quamvis omnes praemissae sumantur in sensu divisionis.	But if such premises are both taken in the sense of division in the first figure, there is always a syllogism regulated by to be said of all or of none when from inherence it is a good syllogism, unless by reason of the mode a negative proposition is included equivalently. Which I say because of this mode ‘false’, and if someone else is similar to himself. Because it does not follow ‘every stone falsely is an animal; every donkey falsely is a stone; therefore every donkey falsely is an animal’. Similarly, this syllogism is not valid ‘every stone being an animal is false; every man being a stone is false; therefore every man being an animal is false’, although all the premises are taken in the sense of division.
Sed alii uniformes valent quando uniformes de inesse correspondentes eis valent et ex modalibus sequuntur suae de inesse. Unde iste uniformis est bonus ‘omnis homo per se est animal; Sortes per se est homo; igitur Sortes per se est animal’. Similiter sequitur ‘omne album dubitatur esse homo; Sortes dubitatur esse albus; igitur Sortes dubitatur esse homo’. Similiter sequitur ‘omne album scitur esse homo; veniens scitur esse albus; igitur veniens scitur esse homo’. Similiter uniformis negativus talis in prima figura tenet, quia regulatur per dici de nullo, et ideo tales uniformes sunt boni ‘omnis forma substantialis scitur non esse qualitas; intellectus scitur esse forma substantialis; igitur intellectus ƿ scitur non esse qualitas’; ‘omnis creatura scitur non esse Deus; creatio scitur esse creatura; igitur creatio scitur non esse Deus’.	But other uniforms are valid when the uniforms of inhernce corresponding to them are valid and follow from the modals their own of inherence. Hence this uniform is good ‘every man is per se an animal; Socrates is per se a man; therefore Socrates is per se an animal’. Similarly it follows: ‘every white thing is doubted to be a man; Socrates is doubted to be white; therefore Socrates is doubted to be a man’. Similarly follows ‘every white thing is known to be a man; a coming thing is known to be white; therefore a coming thing is known to be a man’. Similarly, a negative uniform such as this holds in the first figure, because it is regulated by to be said of none, and therefore such uniforms are good ‘every substantial form is known not to be a quality; the intellect is known to be a substantial form; therefore the intellect is known not to be a quality’; ‘every creature is known not to be God; creation is known to be a creature; therefore creation is known not to be God’.
Si autem maior talis uniformis in prima figura sumatur in sensu compositionis et minor in sensu divisionis, cum aliquo modo tenet respectu conclusionis in sensu divisionis et cum aliquo modo non tenet. Unde iste discursus tenet ‘haec est per se: omnis homo est animal; Coriscus per se est homo; igitur Coriscus per se est animal’. Iste autem non tenet ‘haec est dubitata a Sorte: omne album est homo; Plato dubitatur a Sorte esse albus; igitur Plato dubitatur a Sorte esse homo’.	But if such a uniform major in the first figure is taken in the sense of composition and the minor in the sense of division, when it holds in some way with respect to the conclusion in the sense of division and when it does not hold in some way. Hence this discourse holds ‘this is per se: every man is an animal; Coriscus per se is a man; therefore Coriscus per se is an animal’. But this does not hold ‘this is doubted by Socrates: every white man is a man; Plato is doubted by Socrates that he is white; therefore Plato is doubted by Socrates that he is a man’.
Similiter, si maior sumatur in sensu divisionis et minor in sensu compositionis respectu conclusionis in sensu divisionis, semper tenet, nisi sit talis modus qualis est ‘falsum’. Sed respectu conclusionis in sensu compositionis non tenet: non enim sequitur ‘omne album scitur esse homo; haec est scita: calidum est album; igitur haec est scita: calidum est homo’, sed sequitur ‘igitur calidum scitur esse homo’. Tamen forte cum aliquo modo tenet talis discursus. Sed quia dicere in particulari cum quo modo valet discursus ex una modali in sensu compositionis et alia in sensu divisionis longum foret propter numerositatem modorum, ideo ipsius inquisitionem duxi studiosis reliquendam, quae per dicta et dicenda faciliter possunt sciri.	Similarly, if the major is taken in the sense of division and the minor in the sense of composition, with respect to the conclusion in the sense of division, it always holds, unless there is such a mode as ‘false’. But with respect to the conclusion in the sense of composition, it does not hold: for it does not follow ‘every white thing is known to be a man; this is known: hot is white; therefore this is known: hot is a man’, but it follows ‘therefore hot is known to be a man’. Yet perhaps such a discourse holds in some way. But because to say in particular with what mode the discourse is valid from one modal in the sense of composition and another in the sense of division would be long because of the number of modes, I have therefore decided to leave the investigation of it to the students, which can be easily known through what is said and what is to be said.
Sed in secunda figura pauci tales discursus valent si omnes praemissae sumantur in sensu divisionis. Et ratio est quia tales propositiones de modo raro vel numquam convertuntur in propositiones de consimili modo. Unde non sequitur ‘aliquod album scitur esse homo, igitur aliquis homo scitur esse albus’. Nec sequitur ‘omne album scitur non esse homo, igitur omnis homo scitur non esse albus’. Et quia talis propositio universalis negativa non est convertibilis in illam de modo consimili, nec etiam est convertibilis in illam de inesse universalem sed particularem, ideo talis syllogismus non potest perfici per conversionem universalis negativae, quod tamen requiritur ad hoc quod esset bonus syllogismus ƿ in tali modo secundae figurae. Nec potest etiam perfici per impossibile, sicut posterius ostendetur. Patet etiam per instantiam in terminis quia talis discursus non valet. Non enim sequitur ‘omne album per se est animal; omnis lapis per se non est animal; igitur omnis lapis per se non est albus’. Tamen cum isto modo ‘verum’ est bonus syllogismus. Et ratio est, quia talis propositio de modo et illa de inesse convertuntur. Quando autem non convertuntur, tunc discursus non valet in secunda figura. Sed si una sumatur in sensu compositionis et alia in sensu divisionis, aliquando tenet et aliquando non; sed quando tenet et quando non, discutiant studiosi.	But in the second figure, few such discourses are valid if all the premises are taken in the sense of division. And the reason is that such propositions of a mode are rarely or never converted into propositions of a similar mode. Hence it does not follow that ‘some white thing is known to be a man, therefore some man is known to be white’. Nor does it follow that ‘every white thing is known not to be a man, therefore every man is known not to be white’. And because such a universal negative proposition is not convertible into that of a similar mode, nor is it convertible into that of being universal but particular, therefore such a syllogism cannot be completed by the conversion of the universal negative, which is nevertheless required for it to be a good syllogism in such a mode of the second figure. Nor can it also be completed by the impossible, as will be shown later . It is also clear by the instance in the terms that such a discourse is invalid. For it does not follow that ‘every white thing is per se an animal; every stone is per se not an animal; therefore every stone is per se not white’. However, with this mode ‘true’ is a good syllogism. And the reason is, because such a proposition of mode and that of inherence are convertible. But when they are not convertible, then the discourse is not valid in the second figure. But if one is taken in the sense of composition and the other in the sense of division, sometimes it holds and sometimes it does not; but when it holds and when it does not, let the learned discuss.
In tertia autem figura quando ambae praemissae sumuntur in sensu divisionis et modalis infert suam de inesse, semper sequitur conclusio in sensu divisionis; sicut sequitur ‘omnis homo scitur esse albus; omnis homo scitur esse veniens; igitur veniens scitur esse albus’. Et potest talis uniformis probari sicut probatur uniformis de necessario et de possibili. Hoc etiam probatur per syllogismum expositorium, sicut ibi. Si autem altera sumatur in sensu compositionis et altera in sensu divisionis, si minor sit in sensu compositionis, tenet respectu conclusionis in sensu divisionis.	But in the third figure, when both premises are taken in the sense of division and the modal infers its inherence, the conclusion always follows in the sense of division; as follows ‘every man is known to be white; every man is known to be coming; therefore a coming man is known to be white’. And such a uniform can be proved just as a uniform of the necessary and of the possible is proved. This is also proven by an expository syllogism, as there . But if one is taken in the sense of composition and the other in the sense of division, if it is minor in the sense of composition, it holds with respect to the conclusion in the sense of division.